• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
• /
• pp.1225-1228
• /
• 1987

It is shown that the singularly perturbed continuous-time system is led to two different discrete versions according to slow or fast sampling rates. The design of stabilizing feedback control of singularly perturbed discrete-time stochastic system is decomposed into the design of slow and fast controllers, which is combined to form the composite control. Composite control law is derived for the case of both single rate measurement and multirate measurement.

• 한국지능시스템학회논문지
• /
• 제15권1호
• /
• pp.36-41
• /
• 2005

스마트 스페이스 환경은 유무선 네트워크기반과 다중 센서 기반이며 많은 제어기를 필요로 한다. 이러한 환경을 위해서 본 논문에서는 멀티레이트 디지털 분산 제어 제어기를 제안한다. 제안된 제어기 설계 방법은 디지털 재 설계 기법을 적용하는 것이다. 구체적으로 제안된 기법은 delta-operator와 멀티레이트를 기반으로 하며 선형 행렬 부등식형태로 나타난다. 제안된 기법의 우수성을 검증하기 위해서 스마트 스페이스에서 널리 사용되는 Heating, ventilating, and alt conditioning (HVAC) 시스템에 대해서 모의실험을 하였다.

• 한국지능시스템학회논문지
• /
• 제15권6호
• /
• pp.765-770
• /
• 2005

This paper presents a new intelligent digital redesign (IDR) method via the compensated bilinear transformation to design the digital controller such that the digital fuzzy system is equivalent to the analog fuzzy system in the sense of the state-matching. This paper especially consider a multirate control scheme with a predictive feature, where the digital control input is held constant N times between the sampling points. More precisely, the multirate control scheme is proposed that utilizes a numerical integration scheme to approximately predict the current state from the state measured at the sampling points, the delayed measurements. For this system, the IDR conditions incorporated with stabilizability in the format of the linear matrix inequalities (LMIs) are derived. The superiority of the proposed technique is convincingly visualized through a numerical example.

• 한국군사과학기술학회지
• /
• 제3권1호
• /
• pp.58-65
• /
• 2000

A target signal simulation method for passive sonar systems is introduced. The method uses multirate signal processing techniques to simulate moving target signals in the multi-path sound propagation environment by introducing Lloyd's mirror and Doppler effect. Time and frequency variation of target signal due to the target maneuvering is also considered to provide realistic ship signatures in the LOFAR gram so that the simulated target is used for sonar operator training. Synthesized target characteristics is analyzed and compared with real target signal in terms of interference pattern and frequency variation in the LOFAR gram.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 ITC-CSCC -2
• /
• pp.860-863
• /
• 2002

Realizations of multirate converters are proposed using periodically time-varying (PTV) structures. By exploiting the computational redundancy of the filtering operation in a multirate filter, it is possible to implement the filter with much less hardware. In the proposed implementations, several coefficients time-share in a periodic fashion the hardware of one multiply-and-add. Therefore, each multiply-and-add circuit performs different coefficient scalings at different time instants within a period. Compared to the direct form realization, the proposed realizations reduce the hardware of an interpolator and a decimator by a factor of approximately U and M, respectively, while retaining the same processing speed, where U and M are the upsampling and downsampling factors, respectively. The approach can be used to obtain realizations for sampling rate conversion by a rational factor of U/M, where U and M are relatively prime, in which case hardware reduction by a factor of approximately UM can be achieved.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.174-178
• /
• 1997

In this paper,we consider a LQG problem subject to the stochastic multirate system. By restating the problem as a periodic LQG problem, it is pointed out that the lack of measurements and control inputs in some time instants makes the problem singular. A method of transforming the problem into a nonsingular one enables us to obtain the solution,however which gives a resulting value of the LQG cost and the setimation error dynamic different with those of the original system. As a consequence, we present a optimal value of the original cost and the estimation error covariance of the original system,which are expressed by periodic Lyapunov equation respectively. The evaluation resulte can be exploited in comparing the control system performances and specifying the sampling rates.

• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1996년도 춘계학술대회
• /
• pp.311-314
• /
• 1996

The display of biological signals in monitors often involves a multirate sampling operation which consists of decimation and intenolation. All electroencephalographic (EEG) samples of 10 to 30 seconds must be displayed in the computer screen to keep the aspect ratio of the paper polygraph output. Since the current affordable display technology plots at most 2,000 pixels per row, some samples need to be discarded. This paper studies methods to perform this operation characterizing them from the signal processing viewpoint and compares the display quality among several decimations. Experimental results show that a nonlinear operation such as the peak detection could be preferable than the canonical linear filtering to reduce aliasing.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
• /
• pp.648-650
• /
• 2003

Efficient multi-resolution image fusion aims to take advantage of the high spectral resolution of Landsat TM images and high spatial resolution of SPOT panchromatic images simultaneously. This paper presents a multi-resolution data fusion scheme, based on multirate image representation. Motivated by analytical results obtained from high-resolution multispectral image data analysis: the energy packing the spectral features are distributed in the lower frequency bands, and the spatial features, edges, are distributed in the higher frequency bands. This allows to spatially enhancing the multispectral images, by adding the high-resolution spatial features to them, by a multirate filtering procedure. The proposed method is compared with some conventional methods. Results show it preserves more spectral features with less spatial distortion.

• 대한전자공학회논문지SD
• /
• 제38권12호
• /
• pp.66-74
• /
• 2001

IMT-2000의 무선접속 기술 요소 중 multirate을 위한 Multi-Code(MC) CDMA 시스템의 이동국 Rake 수신기는 다수의 채널로 전송된 신호들을 동시에 복조해야 하므로 Rake Finger에서 트래픽 채널을 복조하는 데이터 상관기의 수가 왈쉬 코드 채널의 수만큼 증가하게 되어 신호처리의 복잡도가 증가되는 단점을 갖게 된다. 본 논문에서는 데이터 상관기들의 증가로 인한 데이터 처리시간 지연을 감소시키기 위해 Walsh Switch, 공유 accumulator, 그리고 파이프라인 FWHT(Fast Walsh Hadamard Transform) 알고리즘을 적용한 새로운 Rake Finger 구조를 제안했다. 컴퓨터 시뮬레이션 결과 왈쉬 코드 채널의 수 에 대한 데이터 상관기의 연산 동작 수는 512 additions에서 160 additions로 약 3.2배 감소하였고, Rake Finger의 데이터 처리시간은 110,696[ns]에서 90,496[ns]로 18.3% 감소하였음을 확인하였다.

• 한국전자파학회논문지
• /
• 제10권2호
• /
• pp.157-168
• /
• 1999

본 논문에서는 이동 무선 시스템 설계시 중요한 채널 할당에 대한 TFS(Time-Frequency Slice)할당 방법 을 제시하였다. 시간-주파수-코드영역을 슬라이스화 하고 요구할당 다중접속(DAMA) 스케줄러를 이용하여 채널을 할당하는 경우 TA (Traditional Assignment) 방식에 비해서 호 차단 확률을 낮추게 된다. 통화량 부 하 $\rho$=0.8이고 요구되는 호 차단 확률이 2%일 때 TA (Traditional Assignment)방식에서는 사용자들에게 11 개의 슬라이스를 할당할 수 있지만. TFS방식에서는 36개의 슬라이스를 할당할 수 있다. 통화량 부하 $\rho$=0.9 일 때 TA방식에서 1%의 호 차단 확률을 기준으로 13개 이상의 슬라이스를 할당할 수 없지만, TFS(TimeF Frequency-Code sliced)방식에서는 40개의 슬라이스를 할당함으로써 TA방식보다 3.07배 향상되었다. 이러한 T TFS방식은 다중속도 사용자들이 많은 시스템구현에 적합한 방법이다.